Microsoft released the intial beta of ASP.NET AJAX today with many, many new enhancements. One of the biggest changes is that the JavaScript files that ASP.NET AJAX controls rely upon to perform their magic have been refactored and significantly reduced in size. For example, the file used to support UpdatePanel operations is now only 6.4k in size which is a huge improvement and should result in pages loading much more quickly the first time they are hit. This release also fully supports the Safari browser which means the UpdatePanel will now work properly with Safari. Opera support is also in the works but not supported at this point. One of my favorites new additions in this release is the ability to dynamically create UpdatePanel controls and inject them into a page's control hierarchy. That feature will prove useful in cases where control developers want to easily AJAX-enable their controls or when an ASP.NET page needs to have AJAX capabilities dynamically added into it.

There are a few changes developers will have to make to any existing ASP.NET AJAX code they may have written using older Atlas releases. One of the biggest is the $() function. This function simplifes the more verbose document.getElementById() method used to locate elements in a page. Due to conflicts with other script libraries (I guess some people like to mix and match several different JavaScript libraries in a page), $() has been renamed to $get() which is a breaking change.

Microsoft's Scott Guthrie posted many more details about the release at the following URL as well as links to where you can download the beta:

http://weblogs.asp.net/scottgu/